1. Field of the Invention
This invention is a simplified airbag module housing which is useful in motor vehicle inflatable restraint systems and is particularly suited for stamped steel construction. The invention is a low cost, unique airbag module that requires only one fastener to complete the assembly, and reduces the total number of module parts to six (6), excluding a decorative cover.
2. Description of the Related Art
Motor vehicle inflatable restraint systems typically include a crash sensor suitably mounted on the vehicle frame and an airbag system or assembly positioned within the vehicle passenger compartment. The airbag assembly generally includes an inflatable cushion and a gas generator, which, respectively, are commonly called an airbag and an inflator. The inflator is a type responsive to a control signal produced by the crash sensor and provides gas to inflate and deploy the airbag upon a sudden vehicular deceleration, sensed by the crash sensor, that is indicative of the onset of a crash.
Also included in the airbag assembly is an outer reaction canister or module housing in which the airbag and inflator are contained. The module housing is a structurally sound member which supports the weight of the folded airbag and the inflator and absorbs and retransmits the airbag deployment forces to the vehicle.
The airbag typically has a section that defines a gas inlet opening for receiving the generated inflating gas upon activation of the inflator. High loads, that is, great amounts of force, are inserted on the airbag and the module housing particularly during the initial stage of inflator activation inflation snap of the airbag. Because of this, secure coupling of the airbag to the module housing is important.
It is generally desirable to reduce the number of fasteners in an airbag system or assembly. Typically, a passenger airbag module, such as the prior art extruded aluminum module housing shown in FIG. 1, is assembled using a plurality of fasteners. The assembly 10 of FIG. 1 includes a reaction canister 12, an inflator 14, a reaction canister body part 16, end caps 18a and 18b, a folded airbag 20, a diffuser plate 22, and a nut 24. A circular opening 26 is provided in end cap 18a and a smaller keyed opening 28 is provided in the end cap 18b. A flange 30 is provided on one end of the inflator 14 and a threaded key stud 32 is provided on the other end thereof. The size of the opening 28 of the end cap 18b is such as to allow the inflator stud 32 to be inserted therein with the inflator flange 30 mating with the opening 26 in the end cap 18a. The diffuser plate 22 supports the folded airbag 20. The open mouth of the airbag 20 is restrained by dowels 34. The nut 24, which is screwed on the stud 32 of the inflator 14, and four fasteners, which attach the end caps 18a and 18b to the reaction canister 12, hold the assembly together. Thus, in FIG. 1 a total of five (5) fasteners are employed to hold the assembly together.
There are many situations where it is desirable to surround the inflator, which is positioned within the module housing, with a retainer tube to help control gas flow to the airbag, contain the pressure, and protect the airbag. The aluminum extruded housing airbag module construction shown in FIG. 1 addresses these problems by utilizing airbag retainer channels and hollow sections. There are many situations, however, where it may be desirable or cost effective to use a stamped steel module housing, such as the prior art typical steel housing assembly shown in FIG. 2.
The assembly of FIG. 2 includes a stamped steel reaction canister 36, an inflator 38, an airbag 40, and an airbag retaining ring 42. Seventeen (17) fasteners are utilized in the assembly of FIG. 2. Most of the fasteners are required for the attachment of the airbag 40 to the reaction canister 42.
Competition in the airbag industry is driving down the price of airbag modules. To be competitive manufacturers must find ways, while maintaining reliability, to produce low cost airbag modules. Three of the best ways to reduce cost are: 1. minimize the number of parts and fasteners; 2. design for easy assembly; and 3. use low cost construction materials. Stamped steel, which, typically, is the lowest cost material for fabrication of structural airbag module components, has been used for airbag module construction, as mentioned above. Stamped steel designs, however, typically, have been labor intensive, requiring multiple fasteners, as shown in FIG. 2. Extruded aluminum designs, as shown in FIG. 1, typically are simpler and easier to assemble but still require multiple fasteners. The extruded aluminum designs also become expensive when multiple secondary operations are required on the extrusion.
There exists a need and a demand for improvement in the construction and assemblage of airbag module housings to reduce the technological gap that exists in respect of the number of parts and fasteners that are required in the assembly of extruded aluminum and stamped steel airbag module housings.